Recover a virtual disk library from the cloud
Posted by Sven Koester, Last modified by Sven Koester on 28 November 2017 12:05

When saving data to the cloud with Backup or Archive, P5 maintains the cloud access through disk volumes in a virtual disk library.
Disk volumes in P5 as listed in the P5 volume manager are represented on disk as a folder in the virtual disk library.
This article is about accessing the data when the disk is lost or inaccessible by any reason.   
As preparation, you need the P5 configuration database that was used on the system and that "knows" about written data. In case that file is missing (for instance in case the whole P5 installation was lost), please check the article first to recover the configuration:
        recover from scratch
Then, you will need to create a folder where the virtual disk library resides.

To do so, look up the folder by opening in P5 the Storage Manager, double click the disk library in question, then check the entry for "Volumes directory:". That is the folder where the disk library was. Either simply create that folder, or, where that is not possible, delete that disk libary and create a new one with the same "Number of container files" and "File size" values.
In case the disk check does not allow that due to missing space, create a smaller disk library and after creation, double click the new entry
and edit the values.
During these step(s), do not label any volumes.  
Next, you will need to identify the volumes you want to restore from.
One way is to start the restore, then the restore job will list the volumes, as an alternative the volumes should be visible in the Volume manager in P5. Normally all disk volumes are listed with their position in the virtual disk libraries, excepts for those on a disconnected external disk. Those volumes left over are most probably those volumes that were on the lost disk.
Now you are ready to proceed:
Create subfolders in the virtual disk library folder, each with the name of a Volume-ID as shown in P5, for instance "10001", "10002" ...
Each folder represents a disk volume, there may be as many volumes as there are slots defined in the virtual tape library.
Then run a barcode inventory in the virtual disk library.

That procedure should make the volume be listed with its position in P5, and - provided the volume exists in the cloud - P5 is able to restore data. During restore the required local information is created in the volume folder.
For volumes that are assigned to a cloud storage WITHOUT local copy, that control information is sufficient and P5 is able to restore and to save data to the cloud.
For those volumes that are assigned to a cloud WITH local copy, each restore job will also rebuild the local copy, but only for the restored files. To completely recover the local volume from the cloud, each file on that volume would have to be restored.
The restore operation may however be written to a temp folder and removed n case the only purpose was to recover the local copy of the volume.

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